Statistics and computer programs for monitoring the progress of genome mapping in humans and other species have been developed. One series of statistics is used to estimate the probabilities of synteny in any pair of species for which gene mapping data are available. Specifically, we have estimates for the probability of synteny (1) within each species, (2) of a pair of loci in one species given their synteny on a specific chromosome in the other species, (3) of a pair of loci in one species given their synteny on any chromosome in the other species, and (4) of a pair of loci in either species given synteny in the other species. We have applied these statistics to updated comparative mapping data, including the human versus mouse map, which now includes 670 autosomal loci. Additionally, we have now devised estimates of the variance of our probability estimates. Computer programs for calculating these estimates are being prepared for distribution. Additional programs for summarizing human cytogenetic mapping data and displaying these data graphically have been improved and used for several reports, including the cytogenetic maps (1) of all known human genes; (2) of all loci corresponding to Centre D'Etude du Polymorphisme Humaine (CEPH) probes; and (3) of all oncogenes, tumor suppressors, growth factors, lymphokines, cytokines, receptors, endogenous retroviral elements, and genes related to any of these.